This invention relates to vibrating screens and more particularly to screen panels and even more particularly to seal strip systems for replaceable screen panels in vibrating screens.
The aggregate industry utilizes many styles of screen machines to sort aggregates by size. Most screen machines utilize vibration to agitate the mixture of aggregates to promote separation through various sized openings in the screening surfaces. Sorting is achieved by undersized particles passing through the openings in the screening surface and the oversize particles being retained above the screen surface. These machines usually have some type of vibrating mechanism to shake the unit and its screening surfaces.
Several layers, or decks, of screening surfaces can be installed in a machine which have screen media of various sized openings to allow sorting of granular material, which is fed into the machine, into several discreet particle sizes.
The screen surface media normally consists of a wire mesh, rigid or flexible panels, with punched or formed holes, all which have specific sized openings to allow passage of sized particles to the decks below, or out the bottom of the screen. The larger sized particles are retained above the surface and are usually discharged on the end opposite the feed end of the deck.
The screen media is normally made in sections to ease removal in order to change opening sizes and also to replace media when worn. The screen surface media is usually stretched in one direction, over a series of support rails. These rails are commonly positioned perpendicular to the stretched direction. These rails are usually positioned to produce a curved profile in order to keep the stretched media pulled into contact with the support rails as the machine vibrates. Without the curved “crowned” profile, and the tension on the media, the flexible media would flutter on the support rails as a result of the vibration, and cause fatigue failure of the media.
The support rails are usually steel bars with a resilient replaceable rubbery cap to provide cushion between the media and the steel support rails. Since the media is normally made in sections, the ends of the media sections, which are perpendicular to the support rails, are either overlapped, or a flat strip is provided below the panel ends to blank the area where the media panels butt together. This strip also provides a surface for the end of the media to rest on. This strip also blocks any oversized material from leaking between the panel ends. This is especially important when sorting smaller particles to prevent contamination of the small passed material with some over sized, retained material that could leak through, in the event a slight gap is present in the butt joint.
The media overlap method is less desirable since it is more difficult to install and also requires removal of the adjacent panels when replacing a worn panel. The support strip, or seal strip as it is commonly referred to, is more desirable since the ends of the media panels simply butt up to each other, making installation and removal of media easy.
These seal strips are usually welded flat bars which can wear out over time. Replacement is difficult since they must be cut from the deck rails and new ones welded in place. They are also difficult to reposition in the event a different length of media panel is desired and the seal strip is desired at different locations.
Consequently, there is a need for improvement in screen panel sealing systems for vibrating screens.